UPAY3FOOD
You pay 3 times for food: the food, the fees, and the difference to the
cheapest option. In Portuguese, “Você paga 3 vezes pela comida”.
Unit pricing for food delivery. In the EU and Australia, supermarkets must
show the price per kilo or per litre. Delivery apps sell the same food without
it. UPAY3FOOD adds unit prices and the three layers to any iFood menu: burgers
per 100 g of meat, drinks per litre, dishes sold by weight per 100 g, food sold
by volume per 100 ml, shared dishes per person. A browser extension reads the
page the user already sees, outlines the item worth buying and takes the user
to it. A public MCP server lets any AI agent do the same math. The calculation
rules are hashed and anchored on Solana, and purchase funding can be shielded
with USDC through Cloak.
Built for the Colosseum Crypto World's Fair hackathon. Not affiliated with
iFood, Rappi, 99Food or Keeta.
What works today
| Area | State |
|---|
| Extension (Chrome, Edge, Brave; MV3) | Reads iFood shop, product and bag pages; shop pages work without login. Calibrated on real pages; regression tests use sanitized captures (commercial data only). |
| You pay 3 times | Food, fees and the difference to the cheapest comparable option, in integer cents. Menu prices are labelled as estimates until the bag confirms them. |
| Price X-ray | Per 100 ml, per litre, per 100 g, per person, and how much of the product the fees are worth. |
| Unit prices for the menu | Burgers per 100 g of meat (with what a combo charges for its extras), dishes sold by weight per 100 g, food sold by volume per 100 ml, drinks per litre within their kind; tubs and 1 kg packs apart. |
| On-page highlight | Outlines the best item per litre and the item the agent picked, on iFood's own menu. |
| Explainable agent | “quero hambúrguer até R$40” (a burger under R$40) → cheapest estimated checkout, best per 100 g of meat and a link to the item; açaí by size works the same way. |
| MCP server | 9 tools + 1 prompt, Streamable HTTP, no login, stores nothing. Works with Claude, ChatGPT, Cursor and other MCP clients. |
| Solana: transparency anchor | SHA-256 of the methodology and of the calculation code, anchored as an SPL Memo on mainnet (slot 455501588); verifiable on /transparencia or with sha256sum. |
| Solana: private funding | 1.000000 USDC shielded into Cloak on mainnet (slot 453687294). |
| Solana RPC | All traffic goes through RPC Fast via a same-origin proxy with a method allowlist; no key reaches the browser. |
| Paying the order's Pix with USDC | Not live. The extension reads the Pix payload; settlement needs a licensed off-ramp partner and stays off until one exists (ADR-006). |
Market board (/market) | Labelled synthetic demo until the observation network is published. Never mixed with real data. |
Rules the product keeps
- Reads only what the user sees, in their own session. No private APIs, no
intercepted traffic, no headless scraping (ADR-007).
- Never orders or pays on its own. The user always confirms.
- No credentials or personal data: no cookies, tokens, addresses, phone
numbers or account data are read, stored or sent.
- Money is integer cents, and ranking uses the checkout total, never the item price alone.
- Observations are not offers, and synthetic data is always labelled.
- Observational language: we show numbers, not accusations about why prices differ.
Repository layout
apps/
extension/ Chrome MV3 extension: readers, popup, on-page highlight
web/ Next.js site: home, install, agents (MCP server at /api/mcp), transparency, docs
observer-api/ observation network ingestion and aggregation
agent-api/ persistent agent runtime (event log, orchestration, SSE)
cloak-cli/ private funding CLI: mainnet shield, balance, dry-run demo
packages/
domain/ money, price layers, per-litre and per-gram math, page-text readers
agent/ intent parser, menu advisor, decision engine
market/ market summary and checkout comparison
pay/ wallet connection, Cloak balance, Solana memo anchor
payments/ Pix BR Code, Solana, off-ramp and Cloak adapters
chain/ Solana RPC boundary (RPC Fast, server side)
fixtures/ deterministic synthetic data for the demo board
docs/ product, architecture, decisions (ADRs), incidents, spikes, proofs
Run it
Requires Node ≥ 20 and pnpm 10 (corepack enable).
pnpm install
pnpm check # typecheck + tests + extension build + site build
pnpm build:extension # → apps/extension/dist, then "Load unpacked" in chrome://extensions
pnpm dev:web # site and MCP server on http://localhost:3000
pnpm demo:cloak # private funding demo (simulated, no wallet)
Without OBSERVER_API_URL, the market board runs on the labelled synthetic demo.
Documentation
How it was built
Built during the hackathon: the repository was created on 2026-10-03 and every
commit is from then on. Development was AI-assisted: many commits are co-authored
with Claude (Anthropic's coding assistant), under the founder's direction and
review. Third-party code is used as dependencies, mainly @cloak.dev/sdk,
mcp-handler, @solana/kit and @solana/web3.js.
License
MIT — see LICENSE.
